Premium Items are items which could only be obtained through a monetary value in Chobots.
Vayersoft introduced Citizenship after Chobots was out of beta on January 21, 2009 . Citizenship was introduced as a in-game membership, allowing users to purchase even more Items, Homes, and Furniture.
To incentivize players into buying Citizenship, it became coming with different tiered packs depending on which option players selected on checkout. These would rotate frequently, usually updating monthly and focusing on a theme for the month that the packs were out. (Ex: October/November months typically featured items like Halloween Costumes, or Thanksgiving Themed Items)
The Premium $hop first appeared on Chobots.net sometime in the summer of 2012, and proved quite popular as a revenue stream. The $hop would typically feature Body, Premium or Rare Items (such as fireboots, which made some users angry), Chat Bubbles, and PlayerCard.
Some Private Server have also had some variant of the Premium $hop or simply shared the same name.